SUBSTANTIATION AND SELECTION OF AN INHIBITOR FOR PREVENTING THE FORMATION OF ASPHALT-RESIN-PARAFFIN DEPOSITS

Abstract

Currently, most oil fields are under the late stage of development, which is associated with some challenges during the production of reservoir products, including the formation of asphalt-resin-paraffin deposits (ARPD) in the “well – bottom-hole formation zone” system. Even though the problem of organic deposits creation has existed for more than 60 years, it is still relevant today. Currently, to prevent the formation of ARPD, inhibitors divided into methods based on the use of wetting agents, modifiers, depressors, and dispersants are widely used infield practice. The composition of inhibitors often includes surfactants, and according to field experience, nonionic surfactants, namely, polyesters, are widely used to prevent the formation of ARPD. However, little is known about inhibitors with a combined effect, for example, possessing depressor-dispersing properties concerning ARPD. Proceeding from the above, the work is aimed to develop a combined inhibitor with depressor-dispersing properties to prevent the formation of ARPD. The dispersing property of the prepared reagent for asphaltene particles was determined using capillary and photocolorimetric methods. The studies were conducted to assess the impact of the reagent on the freezing point. A quantitative assessment of the sedimentation process using the “Cold rod” installation was performed, and the results of studies of the developed ARPD reagent-inhibitor corrosion resistance were presented. Two methods determined the temperature of oil saturation with paraffin: the direct approach – visual observation (Axio Lab A1 microscope) and the indirect approach – rheogoniometry to determine the kinematic viscosity of oil (HVM-472 viscosity analyzer (Walter Herzog GmbH, Germany)). Thus, an ARPD inhibitor (IN-1), comprising a copolymer of ethylene with α-olefins or polymers of acrylic, methacrylic, or cyanoacrylic acid esters, an emulsifier of inverted oil-in-water emulsions and a solvent, was developed. The developed inhibitor, having depressor-dispersing properties, is capable of reducing oil-freezing point in winter and of slowing down the precipitation of paraffin crystals in well equipped and in the bottom-hole formation zone (BHFZ).